Ecology And Environment

Eroded by the Sea

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"Eroded by the Sea"
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Cliffs are constantly being eroded by the sea. The waves throw pebbles, sand and rock against the cliff and over time it forms a cave (this process is called abrasion/corrosion). When back-to-back caves erode fully through a cliff through hydraulic action and corrosion, an arch is left, which links the mainland to a headland. When the arch collapses because it cannot support its own weight or it is continually eroded a stack is left. The stack is an isolated pillar or rock and is often eroded leaving a stump.

A spit is a long ridge of sand and material. It usually continues after a beach has stopped and often curves round. They are formed by the longshore drift in shallow areas. They can change shape depending on the direction of the prevailing wind and subsequently the direction of the longshore drift. The spit itself is the material deposited longshore drift; the material is deposited when the waves don’t have any energy left, and this continual deposition of material forms the spit.

The movement of sediment along the coast is called longshore drift. It usually happens with constructive waves and can only happen if the prevailing wind comes in at an angle and the influential factor is the angle of the sand. As the waves break, the swash carries material up and along the beach, as the swash becomes less powerful, the backwash collects material and sediment straight back down the beach under the influence of gravity. The material is loved in a zigzag pattern

At the foot of the cliff several processes including corrosion (is when a chemical reaction takes place and the sea water dissolves soluble material from the rock), attrition (when rocks rub against each other) and hydraulic action (when air trapped in rocks becomes compressed and expands explosively) attack the base of the cliff to form a wave-cut notch. Joints of cracks from areas of weakness within the cliff, over time the areas of weakness may become enlarged and the cliff collapses. A wave cut platform marks the area where the cliff would have been.

Destructive waves at an exposed coast erode a steep coastal slope through processes like action (when air gets into the cracks in rocks and expands explosively) and abrasion (when rocks erode by rubbing against each other). The waves erode along weaknesses in the rock to form a notch. The continued erosion widens and deepens and sometimes forms a cave the notch and causes its roof to collapse. More undercutting means that the cliff collapses as it can’t support its own weight. This process means that cliffs retreat backwards, over time this creates a wave cut platform. 

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